Internal combustion engine



Malyv 24, 1938'. w. A. MAYNARD v v INTERNAL COMBUSTION ENGINEl Filed sept. v14, 193e PRK f.

Snncntor Gttoreg s Patented May 24, 1938 UNITED STATES PATENT OFFICE l INTERNAL'COMBUsfrIoN ENGINE waltrlA. Mami-cleveland Heights, ohio Application September/14,193.6, Serial No. 1100,596

Va claims. (ci. `12s- 312) My invention is an improvement in internal combustion enginesand relates more particularly vto combustion chambers for the same.

n One of the objects of my invention is to pro- 5 vide a type offconstruction which will induceand maintain an annularrotational swirl ofthe gases in the combustion chamberduring the expansion stroke.

Another object is to' minimize turbulence dur-v ing thecompresslon stroke before ignition and induce maximum turbulenceafter ignition and during the expansion stroke.

Another object of my invention isto means wherebythe compression ratio may be l5 automatically changed as the engine warms up in service. i

A further object -isto -provide a constructionk wherebya part of lthe piston head may be kept at relatively higher temperatures than the main part of the piston. y 'e f o v.

` vA still furtherfobject is to provide a construction/whereby a part of'4 the piston -head may be kept hot during,` operation and so arranged that part of this heat will be dissipated to the air or gas inthe air-cell. p n

' A further object is, to reduce .the amount of heat transferred through the piston and rings to the cylinder wall and jacket while maintaining the temperature of that part of the piston more largely in contact with the main part of the combustion chamber space at a proper temperature.

Another object is to maintain a type of turbulencefwhich, in compression ignition engines, will tend to keep unburned fuel from the cylinder f walls, providing a current of air from the air cell to mix with the combustion chamber gases after they have passed by the hot part of the piston head. A y A A further object is Vto provide a construction 40 whereby a comparatively small and inexpensive i p art will be morel subject .t`o failure vfrom accidentall excessive heat or pres'sure in the combustion chamber and so arranged and proportioned that such small and inexpensive part will fail by a smaller excess of heat or pressure than would provide aw ,reference being made tothe-accompanying drawk ing illustrating these embodiments and in which likeA reference 'characters are employed to designate like parts throughout the same.

yIn the drawing: A Figure 1 is a vertical section ,through a combustion chamber and. associated piston illustratin :one formof my invention.

Figure'Z is a verticall section through a construction illustrating a secondv form of my invention. i

In Figure 1 the `device shown illustrates a general type of construction in which the piston is preferably madeof aluminum or some othermaterial having a relatively higher `rate of expansion under increased heat than the material used for the plate or member dividing .the combustion chamber from the air cell, whereas in Figure 2 is illustrated a device of the general type which may be used where. the relative rate of thermal expansion of the respective parts is reversed, that is,` in which .the plate .or member dividing the combustion chamber from the air cell has a higher rate of thermal expansion than the piston head.

i Either typeof construction may be used where `the relative rates of thermal expansion of plate rand piston are approximately `the 'samek- It isy to be understood that, while the devices illustrated in the drawing and described herein f in detail are designed for use in compression ignition engines, I do not vso limitthe invention,`for itmay alsobeapplied .to other types of internal combustion engines requiring lsome* of `the im'- provements listed above.

4Referring more specifically first to Figure 1, the

piston is indicated at I with the usual packing rings 2. .The piston operates in the cylinder 3 and is formed with a head portion 4.

The head of the piston also includes the up' wardly extending annular wall 5 whichl encloses a chamber 6 in the piston head. f The chamber 6 forms, with thefwall 1 of the cylinder head, ythe combustion chamber,v the` fuel `inlet being indicated generally at 8., rIt isto be noted in the4 form illustrated that the bottomwall 9 of the combustion chamber formedin the piston head is substantially iiat while the side wall I0 leading from the wall 9 upwardly is curved so thatthe greatest diameter of the chamber within the head is at the extreme upper portion. v

. The head 4 .of .the piston is formed with an annular hollow member il threaded to partially receive a cap screw plug I2, the chamber `I3 formed therein having communication with the combustion chamber 6 through one or more ducts I4.

A plate I5 is securely held in place on the member II by means of the cap screw plug I2 as indicated in Figure 1. A spacer member of predetermined thickness is interposed between the member Il and the inwardly extending portions I'I of the plate I5 to regulate the spacing of the outer peripheral edge I8of the plate with respect .to the adjoining surface of the piston head. The washer or spacer I6 may be of a selected material to more or less control the rate of heat exchange between the plate I5 and the piston head. v

It will be seen that .the plate or wall I5 together with the piston head 4 and the lower portions of the side walls I8 provide and enclose an air cell I9 which has communication through the duct I4 with the chamber I3 and .through the peripheral spacing between the plate edge I8 and the wall I0 with the main combustion chamber 6.

'I'he peripheral edge I8 of the plate is surfaced to seat with an adjacent portion I0 of the` piston the spacing of the surfaces I0 and I8 being controlled by the thickness of the washer'or spacer I6, or by selection of materials for the plate I5 and the piston head 4 having diierent thermal expansion ratios. In the embodiment illustrated in Figure 1, I may construct the plate I5 of some relatively low expansive metal or alloy such asnichrome, while the piston may befmade of aluminum. The width of the opening or air passage between the surfaces I0 and I8 will change in proportion to the diierence in operating temperatures and the thermal expansion of these parts.` This may close the opening between I 0 and I8 completely, thus eliminating the air cell I9 volume from the total combustion chamber volume, or by varying the width of opening between I0 and I8 there will be variation in rate of air ow between the air cell and the main combustion chamber.

Diii'erent operating conditions .and requirements may need different adjustments or materials. For. instance, automotive applications may have special need for initial high compression to aid in cold starting and at thefsame time benefit from reduced compression under normal running or operating temperatures or conditions. In such cases materials or adjustments may besuch that the opening or spacing between I0 and I8 is entirely closed when cold, but slightly open when hot.

Other operating requirements may be better served by adjustment and materials which .give a wider opening between I0 and I8 when cool and a smaller opening, with a resultant greater velocity of air through the opening, at higher temperatures. Proper selection of materials and adjustments, will enablethe same type of construction tomeet widely different operating conditions and requirements. v v

In Figure 2, I have illustrated a modication of my invention which is similar in many respects to that shown Lin Figure 1, as, for instance the fundamental relationship of the main combustion chamber 6 and the air cell I9 separated by a plate or wall 20, but having communication by means of the opening 2I.`

In the present embodiment the chamber 22 and plate or wall 20 are formed integral one with the other as illustrated and the bottom Wall of the chamber 22 is secured to the head 4 of the piston by means of a threaded member 23 and a nut 24.

The bottom wall of the,chamber 22 is spaced from the head of the piston by means of a spacer or washer- 25 which may be selected for thickness or for heat conductive qualities to regulate the size of the opening between the peripheral edge 26 of the wall 20` and the adjacent walls I0 or 29 of the piston head. A c ap screw 21 is threaded into the upper portion of the chamber 22 to close the same from above. 'I'he port I4 provides communication between the chamber and the air cell I9 to equalize pressures between the air cell and the chamber 22.

In this embodiment the air cell I9 formed by the plate 20 is substantially the same as that Vshown in connection with the embodiment illuswith the adjacent walls I0 and 29 of the piston,

head. The walls I0 and 29 may converge as shown to form an annular groove or depression 30 in the piston head 4. When the plate is made to close this annular space between it andthe adjacent walls of the piston head, it iszpreferred that the wall 26 first engage the wall 29 in seating relation. Since the higher temperaturesv are present in the combustion chamber 6 when the engine is running, the walls 26 and 29 will thus be less subject to burning or'other destructive action, than the walls 3I and I0. 1

The opening between 26 and I0 or 29 may thus be varied mechanically by selection'of a spacer 25 of desired thickness, or thermostatically by selection of materials having desirable thermally responsive characteristics. In other words, in this embodiment I may construct the piston of iron and the plate or wall 20 of aluminum and thus automatically control the size of the opening between 29 and 26 as a result of the use of materials having diierent thermal expansion ratios.

In both modifications of my invention there is created a novel turbulence of the fuel and/or air in the combustion chamber which may be described as in the nature of an annular rotational swirl. When the piston is at top center at the end of the compression stroke, the pressure of air in both the air cell and the combustion chamber in equalized. Thus when the piston moves downwardly on the expansion stroke, the pressure in the combustion chamber is reduced and air from the air cell will ow out through the annular space between the plate I5 or 20 and the adjacent wall I0 and intothe chamber 6. Up to that time the'air in the combustion chamber is relatively quiescent.

'I'he gas in' the chamber expands downwardly, following the piston, but the annular curtain of air from the air cell, passing out through the annular space above referred to, produces a force 'tending to carry itself and the gas in the combustion chamber up along the cylinder wall, thence across the cylinder head inwardly toward the center thereof and then downwardly toward the piston head. Due to the larger volume and hence greater mass at the outer part of the combustion chamber relative to the axis of the chamber, the slower movement at the circumference produces a faster movement along the axis.

It will thus be observed that an annular rotational swirl is imparted to the air and/or fuel in the chamber by the movement of an annular sheet of vair outwardly of the air cell. In this connection the air cell functions as such and not as a precombustion chamber.

In my invention, the gas along the cylinder wall is blown upwardly away from the piston by the direction of force of the annular jet of air issuing proper fuel or timing producing too high pressures on cold starting.

Various changes in the details of construction and arrangement of parts may be made without departing from the spirit of the invention or the scope of the appended claims.

I claim: v

1. In an internal combustion engine the combination with a cylinder and a piston operating therein, of a member carried by the head of the piston, but spaced therefrom to provide an air cell, said cell having annular peripheral communicationwith a side wall of a combustion chamber formed by the cylinder and piston, said side wall cf the combustion chamber comprising an annular wall extending upwardly from a point below the base of the member carried by the head of the piston and formedr with a concave inner surface, whereby an annular rotational swirl or turbulence of the gases in the combustion chamber will be induced by movement of air from ther air cell along the annular side wall of the combustion` chamber when the pressure in the air cell exceeds that in the combustion chamber, said member comprising a metallic plate having a predetermined coefficient of expansion tending to control or vary the peripheral opening communieating with the combustion chamber in response to variations in temperature in the combustion chamber.

'2. The combination with a cylinder, a fuel nozzle extending axially into the cylinder and a piston operating in the cylinder and having a depression in its head, said depression having an upwardly extending annular side wall formed with an inner concave surface ofa member carried by the piston head within the depression and forming therewith an air cell, said member being normally annularly spaced at its base from the concave side wall of the depression to provide communication between the air cell and the depression, said fuel nozzle being arranged to inject jets of fuel into the depression in the piston head and toward the sides thereof, whereby to impart a uniform anunder load, less heat'lon'theipistonirings', cleaner' "l exhaust, and inexpensive repair in the event of ,fdamageitoi theaircellplate as a result of im tional turbulence will be imparted to the fuel .herein-mailand the depression extend- .,th f

piston head within the chamber and extending radially downwardly and outwardly from the point of attachment toward the lower portion of the chamber side wall, but normally in spaced relation thereto, said member forming an air cell with said piston head, the spacing of said member from the chamber side wall providing continuous annular communication between the said chami ber and air cell, and a fuel injector having an o end projecting into the combustion space and provided with a plurality of restricted radiating ports through which the fuel charge is rsprayed in the form of a cone coaxial with said member.

5. In an internal combustion engine, a cylinder, a piston operable therein, a chamber formed in the head of the piston and having an upwardly extending annular side wall formed with an inner concave surface, an auxiliary air chamber carried by the piston head and having communication with said other chamber through an annular space betweensaid chamber inner surface and the base of said auxiliary chamber, and a fuel injectorin the head of the cylinder adapt-y ed to spray a charge of fuel toward said annular, space and along a wall of said air chamber whereby when there is a greater pressure of the air in the air chamber over the pressure of the gases in the combustion chamber an annular rotaas it approaches said space.

6. In an internal combustion engine, a cylinder, a piston operable therein, a chamber formed in the head of the piston and having an upwardly extending annular wall formed with a concave inner surface, an auxiliary air chamber carried by the piston head and having communication with said other chamber through an annular space between said chamber inner surface and the base of said auxiliary chamber, and a fuel injector in the head of the cylinder adapted to spray 'a charge of fuel toward said annular space and along a wall of said air chamber whereby to impart an annular rotational turbulence to the fuel as it approaches said space, the walls of said auxiliary chamber being responsive to thermal changes to the extent that saidV space between these walls and the said inner` surface of the first chamber may be varied in response to predetermined temperature changes within said rst chamber.

7. In an internalcombustion engine, a cylinder, a piston operable therein, a chamber formed in the head of the piston, said chamber having up- '.wardly extending side walls formed with aconcave surface, a plate generally conical in crosssection carried by said piston Ahead and normally spaced annularly at its base from the side' Walls of the chamber, said vplate forming with said piston head an air cell having communication through said annular space with the chamber,

.and a fuel injector in the head of the cylinder for spraying a fuel charge in the form of a cone toward the chamber concave surface and along the conical plate walls toward the base of the plate.

8. The combination with a cylinder, and a piston operable therein and having a chamber 4 formed in the head thereof, the inner annular side wall of said chamber being formed with a concave surface, of an auxiliary air chamber carried by the piston head, said chamber including a metal plate of substantial conical cross-section normally spaced at its base from the concave surface of said first chamber to provide a passage at the base of the first named chamber` com- Y municating with each of the chambers and a fuel ly extending annular wall formed with a concave innersurface, a plate generally conical in crosssection carried by said piston head and normally spaced annularly at its base from the adjacent concave inner surface of the chamber, said plate forming with saidpiston head an air cell having communication through said annular space with the chamber, said annular space communicating the air cell with the chamber being provided to discharge air from the air cell into the chamber in the form of a continuous sheet along the inner` side walls of the chamber when the pressure of the air in the air cell exceeds that of the gases in the chamber, said plate having portions responsive to thermal changes within the chamber whereby to vary the said annular space between the base of the plate and the adjacent annular side wall of the chamber. y

, WALTER A. MAYNARD. 

